1. Field of the Invention
This invention relates generally to a tray feeder including a corrugated sheet feeding and folding apparatus and more particularly to a new and improved corrugated sheet feeding and folding apparatus and method for rapidly feeding a plurality of corrugated sheets, stacked in a hopper, one at a time to a plurality of conveyance rollers and folding these sheets into a tray carton for receiving articles to be packaged on a packaging machine.
2. Description of the Prior Art
In the art of designing corrugated sheet folding apparatus for tray cartons for use as containers for a plurality of objects such as bottles, cans or the like, at high speed, it is necessary to process each corrugated sheet with minumum hold up time at each stage of the operation, including the feeding, delivery, folding and transporting stages. Any hold-up of the sheet that prevents the processing of the next sheet will slow down the over-all processing of the sheets which is undesirable.
Several types of sheet processing systems have been known and used before, and typical examples thereof in high speed, corrugated preformed sheet folding are shown in the following U.S. Pat. Nos:
______________________________________ Pat. No. Inventor Issue date ______________________________________ 2,745,665 Labombarde May 15, 1956 2,796,256 B. L. Robertson June 18, 1957 3,166,311 J. Rabinow January 19, 1965 3,315,575 A. A. Pinto April 25, 1967 3,429,570 J. W. Scully February 25, 1969 3,625,505 Robert F. Lense December 7, 1973 3,745,892 Robert H. Bant July 17, 1973 ______________________________________
All of the above references show feeding and/or folding devices including hoppers for storage of the blank sheets which are inclined or horizontal to break the vacuum between sheets and the adhesion of the ink printed on the sheets to the next sheet for the extraction of single sheets.
The Labombarde patent teaches a plurality of suction devices 114, 115, 116, 117, working in series with bellows suction 217 to extract sheets stored in an upwardly inclined hopper which slows down the feed process.
The Robertson patent teaches a suction device 12 working in cooperation with gripper jaws 13, 17 to separate and pull sheets from a horizontal stack for placement elsewhere. This process is inherently slow because of the necessity of manipulating the jaws and the coordination of the suction and the jaws to prevent the taking of multiple sheets at one time.
The Rabinow patent teaches the use of vacuum arms 20 and 22 for pulling corrugated sheets away from an upwardly inclined hopper to a pair of jaws having rollers 85 thereon. The use of a vacuum alone to pull the sheets from one to another and the mechanical motion of the jaws inherently slow down the feed process.
The Pinto patent teaches the use of suction means 56 for extracting partially assembled cartons from an inclined hopper, the cartons being held at an upwardly inclined hopper with arms 22, 23 used to support the remaining sheets and attempt to separate individual sheets. The use of mechanical arms 22, 23 inherently slows down the feed process.
The Scully patent shows a plurality of blank sheets 10 stacked in an upwardly inclined hopper and fed downwardly by means of a plurality of spaced feed chains 42. As the foremost sheet reaches the proximity of the feed rolls, the adhesion between it and the next sheet is broken by means of applying a downward pressure at an angle to the top edges of the foremost groups of blanks in order to effect a fanning action on the sheets, with provision being made for directing streams of compressed air against the sides of the foremost groups of blanks in order to counteract the tendency of the blanks to stick together by vacuum.
This approach was used with the type of packaging machine used to package what is known in the art as a "wrap-around package" wherein the carton blank is wrapped completely around the bottles or other objects with its ends being locked in place by various locking means contained on the ends of the carton. Such feeding apparatus as disclosed in the Scully patent was satisfactory for medium carton speeds in the range of 200 to 225 cartons per minute. However, with the advent of higher packaging speeds and newer types of packages, the problems encountered with this type of feeding apparatus have become numerous.
The Lense patent teaches the use of a plurality of suction devices 44 extracting partially completed cartons 10 from a horizontal stack in a horizontal hopper rather than a series of sheets with the inherent problems of vacuum sticking and ink adhesion.
The Bant patent teaches the use of suction device 43 to extract sheets 11 from an upwardly inclined hopper 12 without other provisions for the vacuum sticking and ink adhesion to prevent the feed of more than a single sheet at a time.
The Labombarde, Pinto, Lense and Bant patents also disclose various methods of folding the sheets. The Labombarde apparatus folds the carton in the throat 70-71 of the feed mechanism further slowing down its processing. The Bant apparatus utilizes the wrap-around folding section referred to in the discussion of the Scully apparatus and does not fold conventional cartons. The Pinto and Lense apparati are used for the folding of partially formed cartons rather than corrugated sheets.
With respect to the feeding section of the tray feeder reference is also had to the following patents:
__________________________________________________________________________ Country/Pat. No. Inventor/Applicant Issue Date __________________________________________________________________________ United States 2,540,489 P. R. Pretzer February 6, 1951 Great Britain 3,440 R. E. Machine Co., Ltd. February 10, 1912 Germany 598,809 E. Questor July 16, 1934 __________________________________________________________________________
It is also noted that a typical prior art tray feeder system is schematically illustrated in FIG. 6 which shows inter alia the intermittent, multi-directional flow of the carton blank, which tends to slow the over-all feeding and folding process down.